ZyWALL 5 User’s Guide
Appendix C IP Subnetting
555
A
P P E N D I X
C
IP Subnetting
IP Addressing
Routers “route” based on the network number. The router that delivers the data packet to the
correct destination host uses the host ID.
IP Classes
An IP address is made up of four octets (eight bits), written in dotted decimal notation, for
example, 192.168.1.1. IP addresses are categorized into different classes. The class of an
address depends on the value of its first octet.
• Class “A” addresses have a 0 in the left most bit. In a class “A” address the first octet is
the network number and the remaining three octets make up the host ID.
• Class “B” addresses have a 1 in the left most bit and a 0 in the next left most bit. In a class
“B” address the first two octets make up the network number and the two remaining
octets make up the host ID.
• Class “C” addresses begin (starting from the left) with 1 1 0. In a class “C” address the
first three octets make up the network number and the last octet is the host ID.
• Class “D” addresses begin with 1 1 1 0. Class “D” addresses are used for multicasting.
(There is also a class “E” address. It is reserved for future use.)
Note:
Host IDs of all zeros or all ones are not allowed.
Therefore:
A class “C” network (8 host bits) can have 2
8
–2 or 254 hosts.
A class “B” address (16 host bits) can have 2
16
–2 or 65534 hosts.
A class “A” address (24 host bits) can have 2
24
–2 hosts (approximately 16 million hosts).
Table 12
Classes of IP Addresses
IP ADDRESS:
OCTET 1
OCTET 2
OCTET 3
OCTET 4
Class A
0
Network number
Host ID
Host ID
Host ID
Class B
10
Network number
Network number
Host ID
Host ID
Class C
110
Network number
Network number
Network number
Host ID
Содержание ZyXEL ZyWALL 5
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Страница 44: ...ZyWALL 5 User s Guide 42 ...
Страница 86: ...ZyWALL 5 User s Guide 84 Chapter 3 Wizard Setup ...
Страница 96: ...ZyWALL 5 User s Guide 94 Chapter 4 LAN Screens ...
Страница 102: ...ZyWALL 5 User s Guide 100 Chapter 5 Bridge Screens ...
Страница 130: ...ZyWALL 5 User s Guide 128 Chapter 7 WAN Screens Figure 45 WAN PPPoE Encapsulation ...
Страница 138: ...ZyWALL 5 User s Guide 136 Chapter 7 WAN Screens Figure 50 Dial Backup Setup ...
Страница 144: ...ZyWALL 5 User s Guide 142 Chapter 7 WAN Screens ...
Страница 152: ...ZyWALL 5 User s Guide 150 Chapter 8 DMZ Screens ...
Страница 174: ...ZyWALL 5 User s Guide 172 Chapter 10 Firewall Screens Figure 68 Creating Editing A Firewall Rule ...
Страница 179: ...ZyWALL 5 User s Guide Chapter 10 Firewall Screens 177 Figure 73 My Service Rule Configuration ...
Страница 220: ...ZyWALL 5 User s Guide 218 Chapter 13 Introduction to IPSec ...
Страница 238: ...ZyWALL 5 User s Guide 236 Chapter 14 VPN Screens Figure 110 VPN Rules IKE Network Policy Edit ...
Страница 261: ...ZyWALL 5 User s Guide Chapter 15 Certificates 259 Figure 122 My Certificate Details ...
Страница 280: ...ZyWALL 5 User s Guide 278 Chapter 16 Authentication Server Figure 133 Local User Database ...
Страница 317: ...ZyWALL 5 User s Guide Chapter 19 Bandwidth Management 315 ...
Страница 318: ...ZyWALL 5 User s Guide 316 Chapter 19 Bandwidth Management ...
Страница 352: ...ZyWALL 5 User s Guide 350 Chapter 21 Remote Management ...
Страница 366: ...ZyWALL 5 User s Guide 364 Chapter 23 Logs Screens Figure 188 Log Settings ...
Страница 389: ...ZyWALL 5 User s Guide Chapter 24 Maintenance 387 Figure 210 Restart Screen ...
Страница 390: ...ZyWALL 5 User s Guide 388 Chapter 24 Maintenance ...
Страница 416: ...ZyWALL 5 User s Guide 414 Chapter 27 WAN and Dial Backup Setup ...
Страница 432: ...ZyWALL 5 User s Guide 430 Chapter 30 DMZ Setup ...
Страница 492: ...ZyWALL 5 User s Guide 490 Chapter 37 System Information Diagnosis ...
Страница 508: ...ZyWALL 5 User s Guide 506 Chapter 38 Firmware and Configuration File Maintenance ...
Страница 520: ...ZyWALL 5 User s Guide 518 Chapter 40 Remote Management ...
Страница 536: ...ZyWALL 5 User s Guide 534 Chapter 42 Troubleshooting Figure 343 Java Sun ...
Страница 564: ...ZyWALL 5 User s Guide 562 Appendix C IP Subnetting ...
Страница 570: ...ZyWALL 5 User s Guide 568 Appendix E PPTP ...
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Страница 590: ...ZyWALL 5 User s Guide 588 Appendix G Triangle Route ...
Страница 620: ...ZyWALL 5 User s Guide 618 Appendix J Importing Certificates ...
Страница 622: ...ZyWALL 5 User s Guide 620 Appendix K Command Interpreter ...
Страница 628: ...ZyWALL 5 User s Guide 626 Appendix L Firewall Commands ...
Страница 632: ...ZyWALL 5 User s Guide 630 Appendix M NetBIOS Filter Commands ...
Страница 638: ...ZyWALL 5 User s Guide 636 Appendix O Brute Force Password Guessing Protection ...
Страница 660: ...ZyWALL 5 User s Guide 658 Appendix Q Log Descriptions ...